Turns out you don't actually need an internal drive to run Windows properly.

It's worth noting that Windows is not perfect on the Steam Deck. However, installing the OS or booting it from a microSD Card, can turn it into a nice portable Windows PC. Through this article, you ...

Rufus is an open-source program that creates bootable USB sticks for Windows installation and more. Compared to Microsoft’s Media Creation Tool, Rufus offers many more options for configuration setup.